MINNEAPOLIS — The entire span of an interstate bridge broke into sections and collapsed into the Mississippi River during evening bumper-to-bumper traffic Wednesday, sending vehicles, concrete and twisted metal crashing into the water.

Hometown newspaper The Star-Tribune reported that nine people had been confirmed dead, 60 had been taken to hospitals and at least 20 remained missing early Thursday. The Associated Press put the number dead at seven so far.

"This will be a very tragic night when this is over," Mayor R.T. Rybak said.

From rescue to recovery
By 1 a.m. CT Thursday, Hennepin County Sheriff Rich Stanek said all search efforts had been called off for the night. At about 10:25 p.m. CT, officials said recovery personnel had moved from rescuing individuals to recovering bodies.

About 20 families had gathered at an information center, looking for information on loved ones apparently missing.

Police Chief Tim Dolan said all survivors who were on the bridge are now off.

"We've accounted for all the construction workers except for one," he said.

Rybak said rescue workers had searched around 50 cars. “We have a feeling that there are more vehicles under the water,” Clack said.

"Obviously, this is a catastrophe of historic proportions," said Minnesota Gov. Tim Pawlenty.

The Interstate 35W bridge, a major Minneapolis artery, was in the midst of being repaired when it collapsed at 6:05 p.m. CT. Repairs, which closed at least two of the eight lanes, involved guardrail replacement on the joints and concrete work, Pawlenty said.

At least 60 injured
"There were two lanes of traffic, bumper-to-bumper, at the point of the collapse. Those cars did go into the river," said Minneapolis Police Lt. Amelia Huffman. "At this point there is nothing to suggest that this was anything other than a structural collapse."

MSNBC

Sixty people — at least 10 of them children — were injured, said medical officials. Six individuals being treated at Hennepin County Medical Center were in critical condition, Dr. Joseph Clinton said. He said at least one of the victims had drowned.

Clinton said his hospital treated 28 people. The injuries were blunt force trauma to the abdomen, head, trunk and extremities.

NBC News reported that every Minneapolis ambulance had been requested to the scene.

A freight train was passing under the bridge when it collapsed and was cut in two, witnesses on the scene reported to MSNBC.

No indication of terrorismThe Homeland Security Department said the collapse did not appear to be terrorism-related. The National Transportation Safety Board planned to send a team of investigators to Minneapolis, NTSB spokesman Ted Lopatkiewicz said.

"We continue to monitor the situation. At this time, there's no indication of a nexus to terrorism," Homeland Security spokesman Russ Knocke told NBC News' Pete Williams.

U.S. Transportation Secretary Mary Peters will be flying from Washington to Minneapolis early Thursday morning, NBC News' Jay Blackman reported.

Police set up floodlights so rescue officials could work throughout the night.

The Minnesota Department of Transportation told local media that 200,000 cars a day use the bridge.

The bridge, built in 1967, was last inspected in 2006 and had no major structural defects or deficits, Pawlenty said. "We were told the deck would have to be replaced in 2020."

Pawlenty said the bridge was inspected by the Minnesota Department of Transportation in 2005 and 2006 and that no structural problems were noted. “There were some minor things that needed attention,” he said.

The steel-arched bridge rises about 64 feet above the river.

Police Chief Dolan said officers were checking other bridges as a precaution.

Clinging to a slabA burning truck and a school bus clung to one slanted slab after the collapse.

The school bus carrying 60 children reportedly had just crossed the bridge before the structure crumpled into pieces. The children, who have since been united with their families, exited out the back door of the bus. A Red Cross official said 10 were transported to a hospital.

Christine Swift’s 10-year-old daughter, Kaleigh, was on the bus returning from a field trip and called her mother. “She was screaming, ‘The bridge collapsed!”’ Swift said.

It appeared that the center section of the bridge dropped straight down and pancaked in the middle of the river, leaving several vehicles stranded on a broken island of wreckage. As divers plumbed the waters, other rescuers searched frantically for victims amid broken, zigzagged sections of blacktop. Some of the injured were carried up the riverbanks.

Ritha Boyle, 22, who said she lives about 200 yards from the bridge, witnessed the collapse.

"At first I just heard a big bang and I thought it was thunderstorms," Boyle told MSNBC.com. "Then I looked outside and I noticed there was dust coming up from the bridge, and then I saw it go down and hit a train. I saw some cars trying to hit their brakes and stuff like that, and a whole bunch of cars went down."

Dozens of vehicles were scattered and stacked on top of each other amid the rubble. Some people were stranded on parts of the bridge that weren’t completely in the water.

Many motorists could have been headed to the Minnesota Twins game not far from the bridge.

Thursday’s game postponedThe team postponed Thursday afternoon's game against the Kansas City Royals in response to the incident.

The Minnesota Ballpark Authority also postponed a groundbreaking ceremony for a new stadium that was scheduled for Thursday evening.

The bridge was built with a single 458-foot-long steel arch to avoid putting any piers in the water that might interfere with river navigation.

Catherine Yankelevich survived a 1994 earthquake in Northridge, Calif., and was on the I-35W bridge when it began to shake. “Cars started flying and I was falling and saw the water,” she said. After her car plunged into the river, she climbed out the driver’s side window and swam to shore uninjured.

Workers have been repairing the 40-year-old bridge’s surface as part of improvements along that stretch of the interstate, the Minneapolis Star-Tribune reported on its Web site.

MSNBC.com, NBC News, The Star Tribune, The Associated Press and Reuters contributed to this report.